I. Field of the Invention
The present invention relates generally to fuels and disposal of toxic materials especially the use of high temperature reactants to break down PBB and similar substances such as polychlorinated biphenyls (PCB).
II. Description of the Prior Art
PBB has a structure from ##STR1## where at least two of the bromine molecules shown are present in any of those positions shown. PBB, PCB and similar toxic substances have been used widely in Michigan and other places as fire retardants and for other purposes. In recent years, problems have developed from contamination of farm animals and other objects, both animate and inanimate. This contamination has alarmed citizens because of the potential and actual poisoning of human beings directly and indirectly from the use of PBB. PBB has, therefore, been banned from use in Michigan and attempts have been made to destroy both the remaining supply and items contaminated with PBB. To date no completely satisfactory method has been found.
Many disposals have been made of pure PBB, PCB, and contaminated items at locations throughout Michigan and other states. Some of these disposals were made prior to the discovery of the extreme toxic effects of PBB. At one point, PBB was carelessly added to animal feed which was fed to animals, thereby contaminating such animals (including chickens, dairy cattle, and beef cattle). These animals were thereby rendered unfit for human consumption and had to be destroyed (the milk of the contaminated dairy cattle and the eggs from the contaminated chickens were also destroyed). A great amount of testing was conducted by owners of farm animals to determine PBB contamination. Furthermore, the owners of the worthless carcasses were put to great expense and trouble, not only from the loss of property value in the animals, but also due to the problem of disposal of the carcasses.
The Michigan Department of Natural Resources (DNR), a state agency, was assigned responsibility for disposal of the PBB and contaminated items. In one burial operation at Mio, Michigan, the DNR buried tons of contaminated animals in a "clay-lined" pit. This burial and similar disposals of PBB have caused great controversy among the citizenry and still remain as political "hot potatoes." An alarm has been raised as to potential pollution of water sources with resultant contamination of human beings.
Evidence of increased PBB contamination in humans and its side effects is surfacing regularly. In our tests conducted in conjunction with our copending application Ser. No. 923,054, tests were conducted to analyze the makeup of a typical sewage sludge cake. The tests showed that a sewage sample from Ann Arbor, Michigan contained one (1) part per million (ppm) PBB. This is an alarming figure in view of the fact that few disposal sites are known to exist in close proximity to Ann Arbor. The obvious conclusion is that people have been PBB contaminated by either polluted drinking water or polluted food, although the route of contamination is not known.
Litigation has been started claiming damaging effects of PBB, including birth defects. A recent study indicated that children with higher PBB levels of contamination have a lower learning ability than those with lower PBB levels or those with no contamination. Thus, the problem with PBB disposal has become dramatic. Attempts to burn PBB have been both ineffective and restricted. Burning PBB presents the problem of air pollution from undecomposed PBB in effluent smoke and gases. This, of course, is unacceptable, presenting a quicker route for human poisoning than by burying.
It has recently been determined, however, that decomposition of PBB occurs spontaneously at temperatures in excess of 2000.degree. F. under controlled conditions. Thus, such a disposal is most desirable since no effluent smoke or gas would be PBB contaminated and residue would contain only chemicals which remain after decomposition of the PBB. Although other toxic substances are emitted with the evolving gas from heating PBB, known methods are available for "scrubbing" or otherwise safely recovering such substances.